Pulverizing mill



2 sheets-shea 1 fvufem' Patented pr. `27, 1926,

`UNITED s'rAE PATENT oFFiCE.

FREI) I. RAYMOND, 0F EVANSTON, ILLINOIS, ASSIGNOR TO RAYMOND BROTHERSIMPACT PULVERIZER COMPANY, OF' CHICAGO, ILLINOIS, A CORPORATION 0FILLINOIS.

PULVERIZING MILL.

To all whom t may concern.'

Be it known that I, FRED I. RAYMOND, a citizen of the United States,residing at Evanston, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Pulverizing Mills. ofwhich the following is a specification.

My invention relates to a pulverizing mill from which the material whenground to suicient ineness is removed by an air lift, and moreparticularly to mills of the type involving pendant rollers that arerevolved at a high speed within and in contact with the inner surface ofa grinding or bull ring' between which and the rollers the material isreduced; and the primary object of the invention is to bring aboutaseparation of the finely pulverized material from the larger particlesand the removal of the same from the mill more elfectively,rapidly andeconomically than has been possible heretofore. by providing the part ofthe mill in which the air is admitted with certain novel and improvedconstructions and arrangements for directing the air current against thematerial in a peculiarly advantageous manner.

The invention consists in the new and improved arrangements, devicesandconstructions. to be yhereinafter described and claimed, for carryingout the above stated object and suchv other incidental objects as willbe referred to in the following description of the preferred embodimentof the invention illustrated in the accompanying drawings.`

In the drawings- Fig. l isa vertical sectional view of a mill of thecentrifugal type provided with the air lift arrangements of my presentinvention.

v UI

bearing of shaft 13 is indicated at 17. Suitl able means is provided forsupporting the upper part of the shaft but as the mounting of the. shaftforms no part of my present invention the upper bearings are omitted forthe sake of clearness. Pivo-ted at 18 to a spider 19 fixed to the upperend of shaft 13 are a plurality of roller journals 2O in which arerevolubly supported the shafts 21 of pulveriziiig rollers 22, the latterbeing adapted to bear, through centrifugal force, against a grindingring 23 fastened to an inwardly projecting rib 24 on the wall of themill casing. The. bottom plate of the mill, designated 25, is annulariii-form having a central opening 26 for admission of air to the millfrom air intake duct 27. Arranged above opening 26 and between the saineand the rollers 22 is a deflecting plate 28 secured to the under side ofa spiderJ 29 that is fixed to shaft 13. The deflecting plate is formedwith a plurality of openings or circumferential notches 30 equal invnumber to the pulverizing rollers, through which openings project`plows or scoops 32 fastened to downwardly extending, oblique webs 33 onthe spider 29, the lower ends 34 of the plows working close to theannular bottom plate 25 and their upper ends 35 arranged so as todeliver the material scooped up from plate 25 into the spaces beteen the-rollers and grinding ring in ad vance ofthe rollers. The diameter ofthe delecting plate is substantially' the saine as the interior diameterof the grinding ring. or approximately so. The plate may be slightlylarger as shown in the drawings.

The material may be fed into the mill in any desired manner. I haveshown at the right hand side of Fig. 1 `a rotary feeder 36 arranged in afeeding hopper 37. designates the air outlet which will ordinarily beconnected with some dust-collecting device (not sliown)- Any suitabledevvice may be employed for maintaining the circulation through themill. The lower part of the mill casing is formed so as to provide anannular chamber 39 of larger diameter than the grinding ring anddeflecting plate.

Operatz'omJ-Material fed into-the mill by'- the air from the space atthe center of thev mill compelling it to asslfirst outwardly and thenupwardly andp inwardly in an annular stream which cuts obliquely throughthe stream of material falling from the grinding ring; The finerpartlcles are,in a large measure, picked up by this air current as thematerial falls and are carried off by the air current which finds itsexit from the mill at.38. The remaining material,l including-the'heavier particles, which have not been suiliciently ground falls uponthe deflecting plates 28, being carried inwardly by the air current evenif the plate is of no greater diameter than the internal diameter of theinding ring. Little or none of it falls directly to the bottom ofchamber 39. Of the material falling on plate 28 some of it spills overthe edge of the plate and is subjected again to the separating action ofthe air current, while the rest passes backwardly into'the plow openingwhere it is also given a second air separation which carries the lighterparticles out of the mill. The heavier particles in the bottom ofchamber 29 are scooped by the plows and, with the heavierparticlesfalling on or carried into the low openings, are delivered to thegrinding ring in advance ofthe several rollers.

As a consequence of the arrangements described the finer ground materialis removed from the region where the grinding takes place as soon as ithas been sufiiciently reduced. The two separations in the air which thematerial receives before the heavier particles have fallen to the bottomof the mill, andthe direction of the air current,

which cuts across as well as u wardly through the stream of fallingmaterial, conduce to this .result which adds to the efficiency of bothgrinding and separating operations by ridding the space in which theseoperations take place as completely as possible of the finer particles.The air current acts on the material while suspended in theair, and in avery effective way, so that in comparison with other mills of thisgeneral ty e power may be economized through re uction of the strengthof the air current drawn or forced through the apparatus. There is nochance of clogging through accumulation of material since the plows arecontinually scoopin u the material in chamber 39 through w ic it passesto the grinding chamber. The air does not enter the mill through aseries of openings, as has been customary in mills of this general type,but through a single circular opening which cannot very well becomeclogged up, as is possible with a series of circumferentially arrangedair openings, particularly inasmuch as, in the mill of the presentinvention, the air openin is continually freed of material by operationof the plows. With the old type of mill having a series of air openingsany material that may fall or be forced into the air openings isnecessarily out of reach of the plows, w ereas with the mill ofthis-application the plows operate in a free open space between thecentral air -inlet and the space into which the heavier particles fallso that plows and air current act together to prevent any possibility ofclogging.

Realizing that the principles of my invention might be utilized inmachines different from that disclosed, I wish it to be understood thatthe invention is to be considered as covering all modifications withinthe scope of the appended claims.

I claim:

1. In a pulverizing mill, the combination with a circular grindingsurface, grinding elements cooperatng therewith, an air intake belowsaid grinding surface, and means for feeding the material into the mill;of means for directing the incoming air outwardly and then upwardly andinwardly beneath the grinding surface and through the stream of materialfalling from said Grinding sur face to produce a sepa-ration oi? thematerial as it falls.

2. In a pulverizing mill, the combination with a circular grindingsurface, grinding elements cooperatng therewith, an air intake belowsaid grinding surface,and means for feeding the material into the mill;of means for directing the incoming air outwardly and then upwardly andinwardly through the stream of material falling from said grindingsurface to roducc a separation of the material as it fal s,vand plowsfor scooping up the material collecting in the bottom of the mill anddelivering it between said grinding elements and grinding surface.

v3. In a pulverizing mill, the combination with a circular grindingsurface, rinding elements cooperatng therewith, an air intake below saidgrinding surface, and means for feeding the material into the mill; ofmeans for excluding the incoming air from the cen ter of the mill anddirecting it outwardly and then upwardly and inwardly beneath thegrinding surface and through the stream of material falling from saidgrinding surm5 below said grinding surface, and means for feeding thematerial into the mill; of'means 'for excluding the incoming air fromthe center of the mill and directing it outwardly and then upwardly andinwardly through' the stream of material falling from said grindingsurface to produce a separation of the material as it falls, and plowsfor scooping up the material collecting in thebottom of the mill anddelivering it between the grinding elements and grinding surface.

5. In a pulverizing mill, thecombination of a grinding ring, revolvingpulverizing rollers which travel around and in contact with the ring, anair intake below the rollers, means for feeding the material into themill, and means for directing the incoming air in an annular currentoutwardly and then upwardly and inwardly beneath the ring and throughthe material falling from said ring to produce a separation of thematerial as it falls.

6. In a.pulverizing mill the combination of a grinding ring, revolvingpulverizing rollers which travel around and in contact with the ring, anair intake below the rollers, means for feeding the material into themill; means for directing the'incoming air in an annular currentoutwardly and then upwardland inwardly through the material falling fromsaid ring to produce a separation of the materi'alasit falls therefrom,and means for scooping up the7 material in the bottom^of the mill anddelivering it between the rollers and ring. f

v'Z'. Ina pulverizing apparatus, a casing formed in the. bottom `with acentral .air intake, pulverizing means in said casing, and deflectingmeans arran ed between the bottom of the casing and t e pulverizingmeansfor directing the incoming air first outwardly and then upwardlyand inwardly in an annular stream through the space adjacent thepulverizing means.

8. In a pulverizing apparatus, a casing formed in the bottom with an airintake, pulverizing means in said casing, and defleoting means arrangedbetween the bottom of the casing and the pulverizing means to interceptmaterial falling from said pulverizing means and to direct the incomingair outwardly beneath the pulverizingmeans, and other means to deflectthis air upwardly and inwardly in an annular stream through e the spaceadjacentK the pulverizing means.

9. In a pulverizing apparatus, a` casing the bottom of which is formedwith a centrally arranged air intake, pulverizing means in said casing,and a substantiallyhorizontal deflecting plate arrangedl between thepulverizing meansand said air intake and in the path of material fallingfrom said pulverizing means.

' 10. In a pulverizing apparatus, a casing the bottom of which 1s formedwith a centrally arranged air intake, pulverizing means in said casing,a deflecting plate arranged between the pulverizing means and said airintake andin the pat-h of material falling from said pulverizing means,'and rotary plows which scoop the material from the bottom of the milloutside of said opening and deliver the same to the pulverizing means.

11. In a pulverizing apparatus, a casing 'the bottom of which is formedwith a centrally arranged air intake, pulverizing means Iin said casing,a deflecting plate arranged -below the pulverizlng means and over saidin said casing, and a rotary deflecting plate arranged between saidopening and pulverizing means to direct the air outwardly through thepulverized material, and pro- 4yided with plows which scoop up thematerial in the bottom of the mill and deliverv the same to thepulverizing means, and other means to deflect the air inwardly and`upwardly between the plate and pulverizing means through the pulverizedmaterial.

13. In a pulverizing apparatus, the combination of a casing, the bottomof which i ^is formed with an4 air intake opening, a

grinding rin 1n said casing, a centrally ar` ranged revo uble shaft,rollers carried by said shaft to bear, by centrifugal force, a ainst thegrinding ring, and a deflecting p ate in the. casing between saidrollers and the intake opening the plate being of such diameter that theincoming air flowing therearound must pass first outwardly and theninwardly through the pulverized material falling from the pulverizingvmeans.

I4. In a pulverizing apparatus, the combination of a casing, the bottomof which is formed withv an air intake opening, a grinding ring in saidcasing, a centrally ar# ranged, revoluble shaft, rollers 'cari-led bysaid shaft to bear, by centrifugal force, against the grinding ring, anda deflecting plate on said shaft, the plate being of such diameter' thatthe incoming air flowing therearound must pass first outwardly and theninwardly through the`pulverized mate-v rial falling, from thepulverizing means.

"15, vIn a pulverizing apparatus, the combination, of Xa casing, thebottom of which is formed with an air intake opening, a grinding ring insaid casing, aI centrally arranged, revoluble shaft, rollers carried bysaid shaft A(to bear, by centrifugal force, against the grinding ring, adeflecting plate on said Y with circumferential recesses, and plowswhich are secured, to said plate and extend upwardly in adiagonal-direction through said recesses.

17. In a pulverizing apparatus, the combination of a casing formed witha circular grinding surface and with a chamber of larger diameter belowsaid grinding surface provided with an'l air inlet, pulverizing/elements cooperating with said grinding surface, and a deflecting platearranged in said chamber and extending beneath the grindingsurface andcooperating with the chamber walls t0 direct the infiowing air firstoutwardly and then vupwardly and inwardly through the material fallingfrom said grinding surface.

18. In a pulverizing apparatus, the combination of a casing formed withacircular grinding surface and with a chamber of larger diameter belowsaid grinding surface provided with an air inlet, pulveri'zing elementscooperating with said grinding surface, and a revoluble defiecting platearranged in said chamber and extending bei neath the grinding surfaceand cooperating with the chamber walls to direct the inflowing .airfirst outwardly `and then upwardly and inwardly through the materialfalling from said grinding surface.

1.9. In a pulverizing apparatus, the combination of a casing formed witha circular grinding surface and with a chamber of larger diameter belowsaid grinding surface provided with an air inlet, pulverizing elementscooperating with said grinding surface, and a defiecting plate of adiameter not substantially less than that of the grinding surfacearranged in said chamber between the air inlet and grinding surface.

20. In a pulverizing apparatus, the com` bination of a casing formed,with a circular grinding surface and with a chamber 'of larger diameterbelow said grinding surface provided withi an air inlet, pulverizingelements cooperating with said grinding surface, a defiecting platearranged in said chamber and cooperating with the chamber walls todirect the infiowing air first outwardly and then upwardly and inwardlythrough the material falling from said grinding surface, and meanscarried by the defecting plate for delivering the material in the bottomof the casing to said grinding surface.

21. In a pulverizing apparatus, the combination of a casing providedwith means for pulverizing the material while in suspension in the airtherein and formed with an air inlet in the bottom, and defiecting meansarranged in the path of the material falling from the. pulverizing meansand in the path of the ingoing air, so that the air is directed firstoutwardly and then inwardly beneath the pulverizing means and throughthe falling material, which is subjected to successive air separationswhile suspended.

22. In a pulverizing apparatus, the combination of a casing providedwith means for pulverizing the material while in suspension in the airtherein and formed with an air inlet in the bottom, deflecting meansarranged in the path of the material falling from the pulverizing meansand in the-pat of the ingoing air, so that the air is directed firstoutwardly and then inwardly through the falling material, which issubjectedto successive air separations while suspended, and means forreturning the heavier particles to the pulverizing means.

23. Infa pulverizing apparatus, the combination with a casing, grindingelements in the casing, and means for delivering air into the casing, ofmeans within the casing for causing the incoming air to passsuccessively back` and forth beneath the grinding elements and throughthe pulverized material falling therefrom.l f

A24. cIn a pulverizing apparatus the combination with a casing, grindingelements in the casing, an air inlet 1n the bottom of the casing, andmeans for delivering-air therethrough, of means within the casing forcausing the incoming air to pass successively back and forth 'beneaththe inding elements and through the pulverized material fallingtherefrom.

FRED I. RAYMOND.

